Using some of the world’s most powerful supercomputers, an international team including scientists from several U.S. Department of Energy (DOE) national laboratories has released the highest-precision calculation of a fundamental property of protons and neutrons known as nucleon axial coupling. This quantity determines the strength of the interaction that triggers neutrons to decay into protons—and can therefore be used to more accurately predict how long neutrons are expected to “live.” The results appear in Nature.

“The fact that neutrons decay into protons is a very, very important fact in the universe,” said Enrico Rinaldi, a special postdoctoral researcher at the RIKEN BNL Research Center at DOE’s Brookhaven National Laboratory, who was involved in developing simulations essential to the new calculation. “It basically tells you how atomic nuclei—made of protons and neutrons—were created after the Big Bang.”